Beta is a measure of the systematic, non-diversifiable risk of an investment. The beta coefficient of a security, fund, or portfolio represents its market sensitivity, relative to a given market index and time period. The S&P 500 is commonly used as a market index for such calculations.
Beta is a statistical estimate of the expected average change in an investment's rate of return that corresponds to a one percent change in the market over the time period selected.
A beta value of 0.0 indicates that the investment is risk-free or independent of the market. T-bills are often used as examples of risk-free investments. A value of 0.5 indicates that the security, fund, or portfolio is expected to be only half as risky or sensitive as the average for the market. A value of 1.0 indicates that the investment has the same risk or response as the market, as defined by a market index, such as the S&P 500 or the Russell 3000®. A value of 2.0 indicates that it is expected to be twice as risky or sensitive as the market.
In Russell Style Classification (RSC), beta is calculated as follows:
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Where |
Equals |
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Beta |
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_ |
Benchmark return |
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_ |
Portfolio return |
In Russell Performance Universes (RPU), beta is calculated as follows:
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Where |
Equals |
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Beta |
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n |
Number of observations |
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Rxi |
Market excess return |
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Ryi |
Portfolio's excess return
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